Cenozoic pre- and post-breakup compression in the Faroe-Shetland area, within the context of the NE Atlantic

Johnson, H.; Quinn, M.F.; Kimbell, G.S.; Stoker, M.S.; Smith, K.; Olavsdottir, J.; Varming, T.. 2012 Cenozoic pre- and post-breakup compression in the Faroe-Shetland area, within the context of the NE Atlantic. Edinburgh, UK, British Geological Survey, 79pp. (CR/12/017N) (Unpublished)

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Abstract/Summary

This report is primarily based upon the interpretation of oil industry 2D seismic data, and aims to elucidate aspects of Cenozoic tectonostratigraphic development in the Faroe–Shetland region, especially with regard to post-breakup compression. Evidence of Cenozoic and Late Cretaceous pre-breakup compression and deformation is briefly reviewed. We have utilised established seismo-stratigraphic frameworks and a recently updated scheme for the post-breakup Eocene (Stronsay Group) succession, which are largely based upon the recognition of units bounded by regional unconformities. The seismic expression, extent and thickness of the seismo-stratigraphic units are illustrated by geoseismic profiles, structure contour maps and isochore maps, which are used to analyse the spatial and temporal development of post-breakup compression and deformation within the Faroe-Shetland region. The Faroe-Shetland region records a complex spatial and temporal pattern of departures from the thermal subsidence normally associated with passive margins, including broad uplifts and accelerated basinal subsidence together with fold development up to kilometre scale. The phases of latest Eocene / earliest Oligocene ‘sagging’ (accelerated subsidence) and early Pliocene uplift and exhumation (tilting) appear to be coeval with compression. Indeed, compression appears to have been active throughout post-breakup times, although the loci of deformation have varied both spatially and temporally. Conceivably, some of the large scale sagging, tilting and uplift may be associated with lithospheric folding. Much of the intra-Eocene folding appears to be focused in the southwestern part of the Faroe-Shetland region, around the Munkagrunnur Ridge and Judd area, where phases of shelf progradation are preserved and may be associated with contemporaneous uplift. However, there also appears to be evidence of episodic intra-Eocene and younger uplift in the area around the northern Fugloy Ridge. The overall shaping of the Faroe-Shetland Channel appears to have been initiated at the end of the Eocene, associated with uplift on the Fugloy Ridge and Faroe Platform areas, and with accelerated subsidence in the Faroe-Shetland Basin; this shaping was further developed during the Neogene. A Neogene opening of the ‘Faroe Conduit’ oceanic gateway is favoured on the basis of regional evidence of faunal isolation and restricted environment of deposition together with uncertainty regarding the nature of the ‘Southeast Faroes drift’. A significant phase of Miocene folding is associated with the Intra-Miocene Unconformity (IMU), whereas the Mid Miocene Unconformity (MMU) represents a relatively minor break with a restricted distribution in the NE Faroe-Shetland region. Seabed relief on some folds and late Neogene seismic onlaps may indicate that fold development persisted into Recent times. Lateral offsets and local basin inversion associated with the folding, suggest a strong structural inheritance from the underlying rift architecture. A broad coincidence between the timing of formation of the unconformities and plate reorganisation events in the adjacent Norway Basin and wider region may suggest that these events made important contributions to the forces shaping the margin. The development of Miocene and younger folds may have been influenced by gravitational potential energy / body forces associated with the density structure of the Iceland Insular Margin and the Southern Scandes, or with modulations to ridge-push resulting from transient changes in ridge elevation associated with plume-related temperature (buoyancy) variations in the underlying asthenosphere. Far field stresses associated with, for example, collision between Eurasia and Iberia may also have exerted significant influence on deformation within the Faroe-Shetland region.

Item Type:	Publication - Report
Funders/Sponsors:	British Geological Survey
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed, but not externally peer-reviewed.
Date made live:	09 Jul 2021 10:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530660

Item Type:

Publication - Report

Funders/Sponsors:

British Geological Survey

Additional Information. Not used in RCUK Gateway to Research.:

This item has been internally reviewed, but not externally peer-reviewed.

Date made live:

09 Jul 2021 10:30 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/530660